The Lexus UK blog has a technical interview with RC F chief engineer Yukihiko Yaguchi regarding the decision to stick with a naturally aspirated V8 engine when competitors are moving to turbochargers:

Damion Smy: Why a V8 powerplant when BMW, for instance, has decided to fit a turbocharged six-cylinder?

Yukihiko Yaguchi: First of all, the V8 engine format is the most appropriate for a sports car engine. The reason is that when we talk about sport driving, the torque feel – the acceleration – is most important, and that’s what the V8 format gives. This can also be said for the V10 in the LFA, but if you put under load the torque characteristic [of the V10] is very smooth, but as you go under load it [the V8] gives almost a heartbeat feeling.

DS: How have you managed to avoid turbocharging – or is that a deliberate point of difference for the RC F?

YY: For the ‘F’ brand, the powerplant – the engine – is an important identity, so for this reason we would keep a specifically designed engine. We’ve managed to incorporate detailed electronic control on the intake side of VVT, so at maximum, we are able to finely control the amount of air reaching the engine. What that means is in actual terms is better efficiency.